Seams for use in cloth model
You can use two UV maps. One UV map laid out how ever is best for your model with the main texture. Then a second UV map unwrapped so the cloth seams come out better for painting. 


You can unwrap your model with UV seams and all, make a second UV map then mark all new UV seams and unwrap again.

Here is an old blender nerd tutorial explaining the process. (for people that like video tutorials)

To use your two textures, and two UV maps in cycles, all you need are two UV Map nodes and two Image Texture nodes. Mix the two images together based on the "seams" image's alpha. The image below is a full node setup for using two image and two UV maps.